Automatic switch.



E. H. SCHWARZ.

AUTOMATIC SWITCH. APPLICATION FILED MAY 27, 1912.

1,221,609. 7 Patented Apr. 3, 1917.

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' WWW UNITED STATES PATENT OFFICE.

ELMER H. SGHWARZ, OF NEW YORK, N. Y., ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

AUTOMATIC SWITCH.

Specification of Letters Patent.

Patented Apr. 3, 1917.

Application filed May 27, 1912. Serial No. 699,848;

To all whom it may concern:

Be it known that I, ELMER H. SCHWARZ, a citizen of the United States,residing at New York, county of New York, State of New York, haveinvented certain new and useful Improvements in Automatic Switches, ofwhich the following is a specification.

My invention relates to electric switches, and more particularly toswitches which open automatically upon the occurrence of overload orother abnormal conditions upon the circuit controlled by the switch.

It is customary to control circuits by means of switches which may beopened and closed at will and which in addition are provided with someelectroresponsive latching mechanism by means of which the switch isautomatically opened upon the occurrence of overload or other abnormalconditions on the circuit through the switch. It is desirable that somemeans be provided by which the operator may know whether it is safe toclose the switch, as the apparatus connected to the circuit will beinjured if the switch is held closed while the abnormal conditionspersist. For example, holding the switch closed While there is a shortcircuit would cause severe overloads and strains upon the apparatuswhich supplies current to the circuit. cases been so arranged that theoperator is unable to close the switch as long as the abnormalconditions persist, or, it he does attempt to close it, the mechanismpermits the switch to open again immediately, regardless of the effortsof the operator to hold the switch closed. The mechanism for securingthese results is usually rather complicated and expensive, and a cheaperand simpler form of switch is desirable, if it will enablethe operatorto determine whether the opening of the switch has restored the circuitto its normal condition or whether the abnormal conditions still persistand render it unsafe to leave the switch closed.

The object of my invention is to provide a switch which will openautomatically upon the occurrence of overload or other abnormalconditions and which can ordinarily be closed and opened at will withoutdifficulty but which can be held closed only with great difliculty andeffort on the part of the operator, in case conditions on the circuitare abnormal when the switch is closed. A further object is to provide aswitch which is The switch mechanism has in some in such unstableequilibrium, it closed while conditions upon the circuit are abnormal,that the operator will involuntarily and instantly open it again by theeffort which he makes to close the switch, whereby he is warned thatconditions on the circuit are such as to render it unsafe to keep theswitch closed; which will without effort on the part of the operatorstay closed as soon as the abnormal conditions upon the circuitdisappear; and which is, in many particulars, hereinafter more fullyexplained, an improvement upon switches of this general character.

My invention will best be'understood in connection with the accompanyingdrawing which, merely for purposes of illustration, shows one of thevarious forms in which my invention may be embodied, and in which Figure1 is a longitudinal section through one form of switch embodying anillustrative form of my invention; Fig. 2 is a plan view of part of theoperating mechanism showing the relation of the latching and trippingmechanism to. the remainder of the switch; and Fig. 3 is view partly insection on the line 33 of Fig. 2, showing the latch and a portion of theoperating member with which thevlatch cooperates to hold the switchclosed.

In theparticular form of switch shown in the drawings, the framework 1is secured to a switchboard or panel in any suitable manner and carriesthe various elements of the switch in proper relation to one another. Tothe framework 1 is attached an oil can 2 containing oil or othersuitable insulating liquid in which the circuit is broken. Thestationary contacts 3 mounted on the framework 1 project into the oilcan 2 to a point beneath the surface of the oil and cooperate withmetallic bridging contacts 4 which are carried on rods 5 of wood orother suitable insulating material slidably mounted in the frame 1, tomove vertically to bring the bridging contacts into engagement with thestationary contacts and thereby close the circuit through the switch.Various forms of operating mechanism may be provided for moving thebridging contacts. In the particular form shown in the drawings, therods 5 are secured at their upper ends to the yoke 6 which is pivoted toone arm of a bell crank 7, the other arm of which is connected to anactuating mechanism by which the bell crank is swung about its pivot andthe bridging contacts 4E raised and lowered.

The particular form of actuating mechanism shown in the drawingcomprises a toggle pivoted at one end to one arm of the bell crank 7 andat the other end to the frame 1. This toggle comprises links 8 connectedby means of a pivot 9 to an actuating link or member 10 mounted upon apivot 11 in the frame 1. The actuating member is provided with a handle12 directly or rigidly connected thereto to enable the operator to swingit in a vertical plane about its pivot 11 and thereby raise and lowerthe bridging contacts 4 to close and open the switch. The links 8 and 10form an actuating toggle, and when the switch is closed, as shown inFig. 1, the pivot 9 is slightly below a straight line joining thecenters of the pivot 11 and the pivot of the link 8, so that theactuating toggle is slightly underset and will collapse unless heldrigid by some suitable form of latching mechanism. The relation of theparts is such that if the handle 12 is pressed downward when in theposition shown in Fig. 1, the actuating toggle will go over dead centerwith but comparatively slight resistance and will then permit the switchto open by the folding up of the actuating toggle, due to the upwardmovement of the pivot 9. If the actuating member is released when theparts are in the position shown in Fig. 1, the pivot 9 willautomatically move downward, and in this case also the switch will open,due to the folding up of the actuating toggle as the pivot 9 movesdownward. The

actuating toggle therefore has two extreme switch opening positions, onewhen the pivot 9 is at the limit of its upward travel and the other whenthe pivot 9 is at the limit of its downward travel, a mid or centralposition intermediate the extreme positions when the toggle ispractically on dead center, as shown in the drawings, the switch isclosed, and the toggle can be moved from one side of dead center to theother with comparatively slight effort. Unless some suitable form oflatching mechanism were provided, it would be very difficult for theoperator to keep the switch closed, as the effort which he exerted tostraighten the actuating toggle would be very apt to carry the actuatingtoggle over center, whereupon the switch would open.

In order that the switch may be closed at will without difficulty whenconditions upon the circuit are normal, I provide some form of latchingmechanism which will catch and hold the actuating toggle in the positionshown in Fig. 1 if conditions on the circuit are normal, so that undernormal conditions the switch can be closed as easily as a switch of theusual type. If there is an overload or other abnormal condition existingon the circuit when the switch is closed, the latclr ing mechanism failsto stop and hold the toggle in position to close the switch, and theforce exerted by the operator in closing the switch will carry theactuating toggle right over dead center into the other switchopeningposition. Various forms of latching mechanism may be used, but adesirable form is that shown in the drawings in which the actuatingmember 10 is provided with lugs 13, having between them a recess 14 intowhich the tip 15 of a pivoted latch 16 will fit and stop the actuatingmember in the proper position. As best shown in Fig. 3, the lugs 13 arespaced so far apart that there is considerable lost motion between themand the tip 15 of the latch. The parts are so proportioned that when theactuating toggle is on dead center, the tip 15 of the latch is midwaybetween the lugs 13; but when the actuating toggle is slightly above orbelow dead center but still so near dead center that the switch isclosed, the tip 15 of the latch engages one or the other of the lugs 13and thereby stops the switch in the closed position but with theactuating toggle slightly underset, so that theswitch will openautomatically in case the latch is moved out of the recess 14.

The latch is normally biased to latching position by a spring 17. Inorder to trip the switch, I provide suitable means for moving the latchback into inoperative position either at will or automatically. As shownin Fig. 3, a trip coil 18, responsive to the current flowing through theswitch, is mounted in such relation to the latch 16 that upon theoccurrence of abnormal conditions in the circuit, such as an overload,the latch 16 is attracted by the trip coil 18 against the pull of thespring 17. If an overload appears while the switch is closed, the tripcoil 18 pulls the tip 15 of the latch out of the recess 14- and permitsthe switch to open automatically. The same result can be accomplished atwill by means of a tripping member 19 slidably mounted adjacent thelatch 16 and provided with a cam-shaped tripping surface 20 whichengages the latch 16 and pushes it back when the tripping member 19 ismoved by hand against the tension of its spring 21, which normally holdsit out of engagement with the latch. As long as the contacts are inengagement and an overload exists upon the circuit, the latch 16 is heldso far away from the actuating member 10 that the tip 15 of the latchcannot engage either of the lugs 13. Under these conditions, theactuating member 10 moves as freely as though the latch werenon-existent.

The operation of the device is as follows: lVhen the switch is closed,the parts are in the position shown in Fig. 1 with the actuating toggleslightly underset and the switch biased to open on account of the weightof the moving parts and the resiliency of the contacts. Ir an overloadappears on the switch, the trip coil 18 pulls the latch 16 out ofengagement with the actuating member 10, whereupon the actuating togglecollapses and the switch opens automatically. It the operator attemptsto close the switch while the overload is still present, the trip coil18 is energized the instant the contacts touch, the latch 16 is pulledback out of the way into an inoperative position, and there is nothingto stop and hold operating member 10 near the dead center. its the partsare so proportioned that the actuating member 10 can go over dead centerwith comparatively little resistance, the force exerted by the operatorto close the switch carries the actuating member 10 over dead center,whereupon the switch immediately opens as the actuating member 10 moveson into the other switch-opening position. As long as the overloadpersists, the actuating member 10 can be swung with comparative easefrom one end to the other of its movement, and the switch is closed onlyduring a comparatively small part of the travel of the actuating memberwhen that member is near dead center. As long as conditions on thecircuit are abnormal, the eiiorts of the operator to close the switchwill merely cause the switch to close and then instantly open again,unless the operator makes a deliberate and conscious efi'ort to hold itclosed, and even then he would have considerable dithculty in keeping itclosed, because the latch is held in the inoperative position by thetrip coil 18 and there is nothing to stop the actuating member 10 inswitch-closing position. When conditions on the eiricuit become nor maland the operator attempts to close the switch, the latch 16 is held inits latching position by the spring 17, and, as the opera ing member 10approaches dead center or switch-closing position, the tip 15 of thelatch drops into the recess 14: and thereby automatically stops andholds the actuating member 10 near dead center. The switch is nowclosed, but is free to open automatically as soon as an overload appearsupon the circuit.

My invention may be embodied in many other forms than that shown anddescribed, and I therefore do not limit myself to the precisearrangement disclosed, except in so far as it is limited by the scope ofthe appended claims.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. An electric switch comprising links pivotedto form an actuatingtoggle which is underset on either side of dead center, one of saidlinks having a recess, relatively movable cooperating contacts broughtinto en-' gagement by the straightening of said toggle and held inengagement during movement of said toggle over dead center, and a latchmounted to engage said recess and having an engaging portion narrowerthan said recess, whereby said toggle is stopped on either side of deadcenter in an underset position.

2. An electric switch comprising relatively movable cooperatingcontacts, an actuating toggle for closing said contacts when passingthrough its dead center position and collapsible on either side of deadcenter for opening said contacts, an operating handle directly connectedto said toggle for moving said toggle from either collapsible positionslowly through its dead center position, a latch normally operative torestrain said toggle in circuit closing position, said toggle carrying alatch engaging means movable with said toggle to normally engage saidlatch and permit a limited movement of said toggle on either side or"dead center but to normally hold said toggle in an underset positionwhereby said toggle collapses to open the switch when said latch isremoved.

3. An electric switch comprising relatively movable cooperatingcontacts, an actuating toggle for closing said contacts when passingthrough dead center position and collapsible either side of dead centerfor opening said contacts, an operating handle directly connected tosaid toggle for moving said toggle simultaneously with said handle fromeither collapsible position slowly through its dead center position, alatching member normally biased to latching position to restrain saidtoggle in circuit closing position, said toggle carrying a latchingrecess which normally cooperates with said latching member to permit alimited movement of said to le on either side of dead center but tonormally hold said toggle in an underset position, and means forremoving said latching member to permit said toggle to collapse and opensaid contacts.

4. An electric switch comprising relatively movable cooperatingcontacts, an actuating toggle for closing said contacts when passingthrough its dead center position and collapsible either side of deadcenter for opening said contacts, an operating handle for simultaneouslymoving therewith said toggle from either collapsible position slowlythrough its dead center position, a latching member normally biased in aposition to restrain said toggle in circuit closing position, saidtoggle carrying a latching recess with which said latching membernormally en gages to form a lost motion connection with said toggle andpermit limited movement of said toggle on either side of dead center andto normally hold said toggle in an underset position on either side ofdead center whereby said toggle collapses to open the switch when saidlatch is removed.

5. An electric switch comprising links pivoted to form an actuatingtoggle adapted to be underset on either side oi? its dead center,relatively movable cooperating contacts held in engagement while saidtoggle is in either underset position, an electromagnetically controlledlatch for holding said toggle in either of its underset positions, andan operating handle rigidly connected to one of said links and assuminga mid position when the switch is closed and an extreme position oneither side of said mid position when the switch is open.

6. An electric switch comprising links pivoted to form an actuatingtoggle adapted to he underset on either side of its dead center,relatively movable cooperating contacts held in engagement while saidtoggle is in either nnderset position, an operating handlesimultaneously movable with said toggle from either of two circuitopening positions to an intermediate circuit closing position, a lost 2motion latching means normally biased in position to retain said toggleand handle in said intermediate position and to maintain said toggle ineither of said underset posi tions, and means for releasing saidlatching 2 means to allow said handle and toggle to move simultaneouslyinto either of said circuit opening positions.

In witness whereof, I have hereunto set my hand this 24th day of May,1912.

, ELMER H. SOHlVARZ. Witnesses CLARA E. CosTioAN, MARTIN MARUM.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. G.

